The difference between arc and flashover

1. Electric arc
A self-sustaining gas that conducts electricity, with most of its charge carriers being electrons generated by a single electron emission [GB/T 2900.1-2008]

2. Flashing
Partial breakdown along the surface of solid insulation that occurs in gas, liquid, or vacuum. 【GB/T 2900.5-2008】
Flashover is a destructive discharge that occurs along an insulating surface of a gas or liquid medium under high voltage. The voltage during discharge is called flashover voltage. After flashover occurs, the voltage between the electrodes rapidly drops to zero or approaches zero. Sparks or arcs in the flashover channel cause local overheating of the insulation surface, resulting in carbonization and damage to the surface insulation The discharge along the surface of an insulator is called flashover. The discharge along the interior of the insulator is called breakdown.

The difference between arc and flashover mainly lies in their definition, occurrence environment, and application fields.
（1） Definition
Electric arc: Electric arc is a gas discharge phenomenon that produces instantaneous sparks when current passes through certain insulating media (such as air). Electric arc is a self-sustaining gas conduction phenomenon, where the main carrier is electrons generated by a single electron emission.
Flashover: Flashover refers to the phenomenon of discharge along the surface of a solid insulator when the gas or liquid dielectric surrounding the insulator is broken down. The voltage during discharge is called flashover voltage.
（2） Occurrence environment
Electric arc: usually occurs in gas, when the ion concentration in the gap is high enough, the gap is electrified and an electric arc occurs.
Flashover: When gas or liquid dielectric around a solid insulator is broken down, discharge occurs along the surface of the solid insulator.
（3） Application Fields
Electric arc: Commonly used in high-voltage transmission, welding, electrical equipment and other fields, the application of electric arc requires attention to its safety and impact on equipment.
Flashover: mainly used in power equipment, such as surface discharge of insulators in high-voltage transmission lines and substations. Flashover can cause damage to the insulation performance of equipment.